It is a common practice to mark the position of a golf ball on the green with a coin or a plastic marker. Many golfers carry markers in their pocket or bag, although at times such items are forgotten. Even if one has either item in his pocket, it may still be necessary to sort one out from tees, keys or other pocket contents. As some golf slacks are fitted, getting items from one's pockets can be difficult. These difficulties have been appreciated in the prior art, which has proposed a variety of club-mounted holders for ball markers. Examples are U.S. Pat. Nos. 3,774,913; 3,779,559; 3,791,652; 3,977,674; 4,380,337; and 4,822052. None possess the versatility and ease of use which arises from the present invention. It can readily be applied to a variety of putters so that a ball marker is always available to the putting golfer on the green.